Prior art of possible relevance includes the following U.S. patents, both to Hesse: U.S. Pat. No. 4,378,174 issued Mar. 29, 1983 and U.S. Pat. No. 4,331,201 issued May 25, 1982.
The effort by the automotive industry to reduce the weight of vehicles to thereby improve mileage has seen an increasing use of non-metallic materials in various parts of vehicles. Heat exchangers, more commonly termed radiators, are no exception. While metal materials are still employed in the cores for such heat exchangers because of their greater thermal conductivity over plastics, other heat exchanger components that do not require good thermal conductivity are being made of plastic. A primary example is the so-called tanks which are fitted to the heat exchanger core most typically by securement to the header plates which define the ends of such cores.
Because the joint between the header plate and the tank is one of dissimilar materials, prior techniques of brazing or soldering the joints can no longer be employed. In lieu thereof, to effect the necessary seal, a gasket is disposed between the tank and the header plate and any of a variety of means are employed to hold the components in assembled relation with the gasket under compression to assure a seal at the operating pressures for which the heat exchanger was designed.
It is, of course, necessary that the means employed to effect the connection be strong and long lived to prevent leakage. At the same time, it is desirable that the means be such that disassembly of the component parts can be effected when required for servicing. It is also desirable that the means utilized lend themselves to use in mass production to minimize cost.
Attempts to achieve these objects have resulted in proposals wherein a header plate is provided with a peripheral groove in which the gasket to be compressed may be disposed. The tank is provided with a peripheral flange sized to be received in the groove and adapted to compress the gasket therein. The outer wall of the groove is then deformed in part to overlie the flange on the tank and hold the same in a position compressing the gasket. This approach is exemplified by the above identified Hesse patents.
Unfortunately, because this approach involves deformation of a metal wall which necessarily may be sufficiently thin as to be easily deformed, the same may not always be as strong as might be desired. Pressure within the system during operation will act against the deformed material and tend to deform it back toward its original configuration. When such occurs, the compressive forces exerted on the gasket are lessened and leakage may occur.
In the previously identified co-pending commonly assigned application, there is disclosed an improved connection that obviates these difficulties. Specifically, semispherical tabs are formed to have free edges which overlie a tank flange to assemble the tank compressively against the gasket and the header plate.
This invention constitutes an improvement on that disclosure in the commonly assigned application and is intended to assure that such free edges of the tabs abut the flange over substantially the entire extent of such free edges.